Anthracyclines
Anthracyclines are antibiotics having potent antineoplastic activity, and accordingly they have been used in the treatment of a variety of cancers. The cytostatic effect of most anthracyclines is achieved by affecting DNA functions for example inhibition of RNA synthesis usually by intercalating with DNA.
The group of anthracyclines for example comprises doxorubicin, valrubicin, epirubicin, daunorubicin and idarubicin. Doxorubicin and epirubicin have been applied against a broad spectrum of neoplastic diseases, whereas daunorubicin has primarily been applied against acute leukemia. Doxorubicin, daunorubicin, idarubicin and epirubicin are usually administered systemically by injection. Systemic administration of these anthracyclines however results in a number of undesirable side effects such as cardiotoxicity and bone marrow suppression.
Anthracyclines are in general known to be very tissue toxic. For example, paravenous injection of epirubicin results in severe necrosis and immediate measures have to be undertaken to avoid severe local toxicity.
Valrubicin is a semisynthetic analogue of doxorubicin and it is developed for the treatment of superficial bladder cancer and approved for such use in the United States. Usually a total of 800 mg is administered by 40 mg/ml intravesical instillation of two hours duration for a total of 6 times once a week. Such a treatment does not result in systemic uptake, but valrubicin may be found in an effective concentration 1800 μm into the epithelium of the bladder (7).
Psoriasis
Psoriasis is characterised by epidermal hyperproliferation including a highly increased growth of keratinocytes. Furthermore, parakeratosis, i.e. cell nuclei retained in stratum corneum may always be observed in psoriatic patients. With increased cell proliferation, there is an increased DNA synthesis in the affected tissue which has been the basis for assays for evaluation of the efficacy of anti-psoriasis agents.
Treatment of psoriasis depends on the kind of psoriasis and the degree of severity of the psoriasis to be treated. Psoriasis vulgaris, guttate psoriasis, flexural psoriasis, erythrodermic psoriasis, generalised pustular psoriasis and localised pustular psoriasis are the most common forms of the disease.
Commonly used treatments against psoriasis may for example be                Local treatment with vitamin-D derivative ointments or creams. Vitamin D is slow working and can cause temporary skin irritation.        Local treatment with steroid ointments that may inhibit inflammation associated with psoriasis. Common side effects of steroids include thinning of the skin, easy bruising and stretch marks. Furthermore, administration of steroids often results in rebound phenomena.        Coal tar ointment or coal tar baths that may inhibit inflammatory processes in the skin. Coal tar may make the skin more sensitive to ultraviolet light and tar products stain clothing and linens, and may be irritating to the skin.        Potassium-permanganate baths that have a disinfecting effect.        Climatotherapy, for example sunbathing and bathing in saltwater for example at the Dead Sea. However 10% of psoriatic patients are hypersensitive against sunlight and sunburn can cause psoriasis to get worse. Furthermore, sunbathing increases the risk of skin cancer.        
These treatments are frequently not effective and especially more severe cases of psoriasis cannot be treated using the above mentioned treatments. More severe cases of psoriasis may instead be treated with light therapy which, however, must be performed at the hospital or clinic. Light therapy can for example be:                Ultraviolet light treatment (UVB), which especially is applied in cases where the psoriasis is widespread, but not very thick, because UVB can not penetrate a thick layer.        Ultraviolet light and tablet treatment (PUVA) that is a combined treatment involving administration of 8-methoxypsoralen that increases the sensitivity of the skin towards UVA therapy and therapy with UVA. The side effects of this treatment involve nausea and in certain cases increased biochemical liver values. Moreover UVA irradiation results in an increased risk of skin cancer and premature ageing of the skin        
Very severe cases of psoriasis that may not be effectively treated with either of the above mentioned treatments may be treated with a systemic treatment agent such as for example:                Methotrexate—a cytostatic, which is also used in the treatment of cancer. The dose is lower than what is used in cancer treatment. Short-term side effects of methotrexate include nausea, fatigue, loss of appetite and mouth sores, whereas long-time side effects may include damages to the liver.        Sandimmun/cyclosporin—an immune inhibiting compound that is also used in organ transplantation that inhibits the abnormal immune processes in the skin of psoriatic patients. Side effects may be severe. They are similar to the side effects caused by other cytotoxic agents and include myelosuppression, decreased resistance to infections and risk of secondary neoplasms.        Acitretin—a vitamin A like compound that inhibits inflammation. Acitretin is only effective against pustular and erythrodermic types of psoriasis, and increases the risk of causing birth defects in developing fetuses.        
The side effects of these treatments are considerable and hence it is not desirable to use any of these treatments to frequently.